1. Field of the Invention
The present invention relates to connecting devices for electrically connecting lead terminals of electronic devices such as cold cathode fluorescent lamps.
2. Description of the Related Art
As this kind of connecting devices, there is one in which a contact to be accommodated in the body includes a first connection part adapted to elastically hold a lead terminal of an electronic device in between, and a second connection part for connecting to a substrate.
For example, as a first connecting device, there is one as disclosed in Japanese Unexamined Utility Model Publication No. 06-17123, in which a first connection part includes a fixed piece and a curved movable piece having a rectangular hole into which the fixed piece is inserted. The device is adapted such that when the movable piece is press-operated, a space is formed between a wall face of the hole and the fixed piece, so the lead terminal is inserted into the space so as to be held between them.
As a second connecting device, there is one as disclosed in Japanese Unexamined Patent Publication No. 2003-77558, in which a first connection part includes a fixed bracket to be mounted to an accommodation part of the body, and an almost reverse L-shaped movable piece movable vertically with respect to the top end face of the fixed bracket, and an operation member for moving the movable piece. The device is adapted such that when the movable piece is pressed by the operation member, a space is formed between the tip part of the movable piece and the top end face of the fixed bracket, so the lead terminal is inserted into the space so as to be held between them.
As a third connecting device, a first connection part is a coil spring to be accommodated in the body as disclosed in Japanese Unexamined Patent Publication No. 09-92018. The device is adapted such that the coil spring is to be compressed to form a space between one end part of the coil spring and the inner wall face of the body, so the lead terminal is inserted into the space so as to be held between them.
However, the first connecting device has such a configuration that the curved movable piece always abuts an inner wall face of the body. Namely, the elastic force of the movable piece always acts on the body continuously, so the body may be deformed, involving an essential shortcoming that it is not suitable for long-term use.
The second connecting device is adapted to hold the lead terminal between the tip part of the movable piece and the top end face of the fixed bracket, so after the lead terminal is mounted, the elastic force of the movable piece continuously acts on the body through the lead terminal and the top end face of the mounting bracket. Therefore, the second connecting device also has the same shortcoming as that of the first connecting device.
The third connecting device is adapted to hold the lead terminal between an end part of the coil spring and the inner wall face of the body, so after the lead terminal is mounted, the elastic force of the coil spring continuously acts on the body through the lead terminal. Therefore, the third connecting device also has the same shortcoming as that of the first connecting device. Moreover, in forming a space for mounting the lead terminal between one end part of the coil spring and the inner wall face of the body, the coil spring must be compressed by pressing the lead terminal against the coil spring. The elastic force of the coil spring thus causes an unnecessary load applied to the lead terminal when being mounted. Therefore, the device involves another shortcoming that the lead terminal or the electronic device having the lead terminal may be damaged.